In an earthquake early warning distribution infrastructure for mobile radio communication (e.g., CBS, ETWS, and CMAS), by broadcasting information by a simultaneous broadcasting signal, a warning can be quickly made to a broad range of users, without establishing dedicated channels for corresponding users. As the simultaneous broadcasting signal, for example, a paging signal through a Common Control Channel (CCCH); a reporting signal through a Broadcast Control Channel (BCCH); or a signal (e.g., BMC) through a Common Traffic Channel (CTCH) may be considered.
Usually, broadcast information, which is broadcast during an earthquake and tsunami, for example, is transmitted by transmitting a Primary Notification signal and subsequently transmitting a Secondary Notification signal. The Primary Notification signal provides advance notice of broadcasting of emergency information by minimum information, such as “earthquake” or “tsunami.” The Secondary Notification signal indicates details (emergency information), such as seismic intensity in each place and an epicenter. In this manner, by dividing information broadcasting into two steps, broadcast information can be quickly and flexibly broadcast. As an example, the Primary Notification information is transmitted through the common control channel (CCCH), and the Secondary Notification information is transmitted through the common traffic channel (CTCH).
For a case of a mobile communication system, such as based on the wideband code division multiple access (WCDMA) scheme, user equipment (UE) which is in an idle (IDLE) mode (in which a connection is not established) or in a paging (Cell_PCH) mode (in which connection is not released but no user data is transmitted nor received) can properly receive the common traffic channel (CTCH). However, user equipment (UE) which transmits and receives user data (which UE is in a cell DCH (Cell_DCH) mode or in a cell FACH (Cell_FACH) mode) performs communication without referring to the common traffic channel (CTCH). Accordingly, a problem is that a user of the user equipment, whose communication mode (RRC protocol state) is the Cell_DCH mode or the Cell_FACH mode, may not quickly notice existence of broadcast information, or even if the user notices it, the user may not properly receive it. Non-Patent Document 1, for example, discloses that user equipment in a specific RRC protocol state can receive broadcast information.
To address this problem, it can be considered to design user equipment (UE), so that it can receive the common traffic channel (CTCH) even in a state (Cell_DCH) in which a dedicated channel is established, for example. However, if such a function were mandatory for user equipment (UE), the user equipment would be required to always monitor the common traffic channel (CTCH), in addition to transmission and reception of user data. Consequently, the concern would be that the battery energy would be consumed quicker, and that cost of the user equipment (UE) would be increased.